A fuel cell hybrid vehicle, which is an environmentally-friendly future vehicle operated by continuously producing constant power by a fuel cell, and that employs an operation mode when the power is not sufficient, an electric vehicle (EV) battery auxiliary outputs a shortfall of power.
A voltage range of a fuel cell, which is a main power source, is greatly different from a voltage range of the EV battery, which is an auxiliary power source in the related art. Therefore, a bi-directional high voltage DC/DC converter (BHDC) is necessary in order to control charge and discharge of the EV battery. The BHDC includes input/output capacitors, input terminal inductors parallel with the capacitors, and six power switches. It also controls a bi-directional movement of the current according to a voltage command of an output terminal of a controller. The BHDC is interfaced with a control board, a switching mode power supply, a snubber circuit, and an input/output terminal branch high voltage connector. It employs a forced air cooling since regular current bi-directionally flows. The BHDC supplies voltage to a balance of plant (BOP) of the fuel cell by boosting the voltage of the EV battery when a vehicle starts. When the vehicle is in an idle state or is regenerative braking, the BHDC charges current to the EV battery, and the BHDC discharges current when a motor is running.
As described above, since the BHDC includes a plurality of constituent elements, the BHDC is manufactured as an independent component to be connected to a power net system by using a high voltage connector. Further, a control circuit has complex design due to the plurality of constituent elements, thus deteriorating stability and increasing volume, weight, and cost of the power net system.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure, and therefore may contain information that does not form the prior art known in this country to a person of ordinary skill in the art.